1. Field of the Invention
This invention relates to a lacrimal outflow system filler mechanism and, more particularly, to an apparatus, kit, and method for treating dry eyes by creating an occlusion in the lacrimal outflow system.
2. Description of the Related Art
Human tears include three basic components: (1) lipids; (2) an aqueous component; and (3) mucin. The absence of any one of these components causes discomfort in the eye. While tears are eliminated through various methods in the human eye, tear evaporation accounts for 20% or more of tear elimination within the tear film in adults.
A proper tear film is essential for maintaining eye health. Our eyes require moisture to wet and smooth the ocular surface to provide clear vision. Lacrimal secretions from the tear gland also protect the eye by washing away hazardous materials as well as providing important enzymes to fight infections. The pH for the tear film is maintained between 6.5 and 7.6.
The tear film is a complex structure composed of three layers: (1) an outer lipid layer; (2) a middle aqueous layer; and (3) an inner mucinous layer. The outer layer, produced by the Meibomian glands, prevents the tears from evaporating. The middle layer, produced by the lacrimal gland and accessory gland, wets the eye. The inner layer, produced by the conjunctival goblet cells, is responsible for spreading the tears out evenly. These three layers must be in a delicate balance to maintain a proper functioning tear film.
The human eye utilizes the lacrimal system to maintain the delicate balance of the tear film. The lacrimal system includes a lacrimal gland and a lacrimal tear duct. The lacrimal gland is analogous to a faucet within the lacrimal system. The lacrimal tear duct is analogous to a sink drain. The “faucet” works with the “drain” to maintain the balance within the tear film in the eye.
Hyaluronic acid (HA) is a natural, colorless, odorless gel that has various FDA approved, medical applications, including applications that relate to the tear film and to the eye in general. HA has been used for years by cataract surgeons. The surgeons inject the HA directly into the eye to maintain eyeball shape during surgery. HA is removed from eye through the use of an enzyme called hyaluronidase at the conclusion of surgery.
Many publications disclose applications for treating dry eyes using topical HA or HA solutions. The abstract entitled “Effectiveness of hyaluronan on corneal epithelial barrier function in dry eye” in Br. J. Ophthalmol 1997, 81:533-536 (July) indicates that HA can be utilized as a lubricant to improve the corneal epithelial barrier function in eyes.
HA also has several medical uses that do not relate to the eye. The article entitled “Re: What is Hyaluronic Acid” downloaded from the website www.madsci.org on Feb. 15, 2009 discloses that HA is the major component of cartilage and joint lubrication. A publication entitled “Nourish Your Skin from the Inside Out with Hyaluronic Acid and Collagen” downloaded from the website www.smart-publications.com on Feb. 15, 2009 indicates that HA can be used a dietary supplement. A publication entitled “Hyaluronic Acid Review” downloaded from the website www.beautyproductscompared.com on Feb. 9, 2009 indicates that HA can be injected into the body.
Recently hyaluronic acid has been utilized as an injectable filler to fill wrinkles in the face. HA is a natural mucopolysaccharide that provides scaffolding for collagen in the body. HA is a repeating chain of simple sugars that are the same in all mammals and, therefore, are well tolerated and do not require testing for allergic reactions. They have a unique property of being osmotic, or swell and draw water with them. The amount of HA decreases as we age and, therefore, we loose its plumping and lubricating benefits.
Several applications that use HA to treat dry eyes have been disclosed. Dry eyes can be associated with the dysfunction of the lacrimal gland that causes it to supply insufficient moisture to the eyes. The resulting condition of dry eyes, commonly referred to as dry eye syndrome (DES), is heralded by a gritty, irritated ocular sensation as well as visual deterioration. DES can become so severe that corneal decomposition, ulceration and permanent visual loss can ensue. DES is a common condition that affects millions of people every year.
The tear film utilizes HA as a moisturizer and lubricant. Adding HA topically to tear replacement solution has been reported to be beneficial in treatment of dry eyes. Several publications have disclosed HA solutions that are used as eye lubricants, such as an abstract entitled “Effect of hypotonic 0.4% hyaluronic acid drops in dry eye patients: a cross-over study” by P. Troiano and G. Monaco, Cornea, 2008 Dec. 27 (10): 1126-30, an abstract entitled “Carbomer and sodium hyaluronate eyedrops for moderate dry eye treatment” by M. E. Johnson et al., Optom. Vis. Sci. 2008, August: 85(8): 750-7, an abstract entitled “Performance profile of sodium hyaluronate in patients with lipid tear deficiency: randomized, double-blind, controlled, exploratory study” by P. Prabhasawat, Br. J. Ophthalmol. 2007 January 91(1): 47-50 (E-Published Sep. 14, 2006), and an abstract entitled “Effectiveness of sodium hyaluronate eyedrops in the treatment of dry eye” by M. E. Johnson et al., Graefes Arch Clin Exp Ophthalmol. 2006 January 244(1): 109-12 (E-Published Jun. 28, 2005).
Several publications are directed to the use of HA as lubricants or eye drops include the abstract entitled “Cytoprotective effects of hyaluronic acid and Carbomer 934P in ocular surface epithelial cells” by C. Debbasch et al., Invest. Ophthalmol Vis. Sci. 2002 November 43(11): 3409-15, and the abstract entitled “A randomized, crossover, multicentre study to compare the performance of 0.1% (w/v) sodium hyaluronate with 1.4% (w/v) polyvinyl alcohol in the alleviation of symptoms” C. C. McDonald et al., Eye, 2002 September, 16(5): 601-7, and the abstract entitled “Sodium hyaluronate eye drops of different osmolarity for the treatment of dry eye in Sjögren's syndrome patients” by P. Aragona et al., Br. J. Ophthalmol 2002, 86(8):879-84 (August), “Hyaluronan in dry eye and contact lens wearers” by Berry M. Pastis et al., Adv. Exp. Med. Biol. 1998; 438: 785-90 (abstract unavailable), and the abstract entitled “Sodium hyaluronate eyedrops enhance tear film stability” by T. Hamano et al., Jpn J. Ophthalmol 1996; 40(1): 62-5. Publications that disclose the use of HA as an artificial tear substitute include the abstract entitled “Long term treatment with sodium hyaluronate-containing artificial tears reduces ocular surface damage in patients with dry eye” by P. Aragona et al., Br. J. Ophthalmol 2002, 86(2):181-4 (February).
While these treatments may provide temporary relief to DES, these treatments are ineffective against many forms of DES. Keratitis sicca (or keratoconjunctivitis sicca) is the most common form of dry eyes. Some forms of keratitis sicca affect only the lacrimal gland and cause decreased tear production. Other forms affect the mouth by causing dry mouth.
Keratitis sicca occurs most commonly in women in the fifth and sixth decades. Symptoms include foreign body sensation, burning, irritation, pain and photophobia. Clinical signs include conjunctival injection giving rise to red eyes, and decreased tear film and corneal epithelial keratopathy on slit lamp exam.
The diagnosis of dry eyes and keratitis sicca is confirmed with decreased tear meniscus. The inferior tear meniscus height is normally 0.2 mm. A decreased tear film break-up (TFB) is another sign. TFB is defined by the time between the blink and the appearance of the first corneal dry spot appearing. A value less than 10 seconds is abnormal.
Another sign of DES is the staining of the cornea with flourescein or Rose Bengal. A Schirmer's test is often used to detect DES. A strip of filter paper is placed on the eye hanging over the lower lid to wick the tears. A measurement of less than 5 mm in 5 minutes can indicate a dry eye.
DES has a variety of causes but in general insufficient tears are produced to maintain an adequate aqueous layer. DES cannot be treated by merely stimulating the lacrimal gland to secrete more tears. Since it is not possible to increase lacrimal gland flow or turn the faucet higher, practitioners rely on adding moisture or blocking the outflow of tears away from the eye to create a wetter ocular environment.
A common type initial medical treatment for DES involves replacing moisture with artificial tears and ointment. One method involves adding wetting drops from artificial tear bottles to help reverse the dryness. Although artificial tears bring temporary relief, the manufactured solutions do not have the same composition as natural tears, so that the artificial tears are not as beneficial as a person's own tears.
Artificial tears have several other disadvantages. One disadvantage of artificial tears is the increased risk of allergies to preservatives within the artificial tears. This can be alleviated through the use of preservative-free tears for sensitive eyes.
Another disadvantage of artificial tears is that the relief tends to be short-lived. As a result, the treatment must be re-administered several times each hour, which is usually not practical.
Other treatments for dry eyes include night time lubrication with heavy ocular ointments, ocular moisture chambers, lid taping for improved closure, or eyelid surgery to aid in decreasing the open exposure of the eye.
The risk of DES also increases with increasing age. The application of drops by elderly patients can be challenging due to decreased dexterity, which represents another disadvantage of this approach.
Since we cannot increase tear production, an alternative approach involves slowing down the drainage of the tears through the lacrimal ducts by blocking the drain. The lacrimal outflow system is a series of tubes that serve to remove tears from the eye through the nose. Initially, tears drain from the eye through the upper and lower punctal openings, which lead into the canalicular canals, and ultimately to the lacrimal sac. It is in the lacrimal outflow system that drainage of tears from the eye can be adjusted.
Early attempts at sealing the puncta and/or the canalicular canals involved stitching the puncta shut, using electrical cauterization, or laser cauterization of the puncta and/or the canaliculus. Although these methods can provide an acceptable decrease in tear drainage, these methods may be difficult, painful, or irreversible without reconstructive surgery.
Sealing the tear ducts with cautery is painful and can be invasive and, potentially, irreversible. Since it is sometimes difficult to determine whether in a particular patient the drainage is too great or the tear production is too small, irreversible blockage is not desirable.
Punctal plugs or punctal occluders are solid silicone cylinders that are a popular method of first line treatment of DES. They act like a solid rubber cap in a sink drain. Such plugs or occluders have been disclosed by EagleVision, Enteroptyx, and Grace Medical of Memphis, Tenn., Odyssey Medical of Bartlett, Tenn., and Oasis Medical of Glendora, Calif.
Various punctum plugs have been disclosed by EagleVision, Enteroptyx, and Grace Medical of Memphis, Tenn. in their brochure entitled “Opthalmic Products.” The plugs are the conventional silicone plugs with a tapered lower portion, a flanged upper portion, and a shaft-like connecting portion. The lower portion is inserted into the puncta. The connecting portion connects the lower portion to the upper portion.
A similar punctal plug has been disclosed by Odyssey Medical of Bartlett, Tenn. The plug includes the tapered lower portion, the flanged upper portion, and the shaft-like connecting portion.
U.S. Pat. No. 5,830,171 discloses a punctal occluder for blocking the flow of lacrimal fluid from the surface of an eye through a lacrimal punctum. The punctal occluder includes a shank having a distal end for insertion into the lacrimal punctum. The punctal occluder also includes a distal flange attached to the distal end of the shank for insertion into the lacrimal punctum. The distal flange includes a wing portion that has a first position extending substantially along the shank for allowing easy insertion of the distal flange into the lacrimal punctum. The distal flange also has a second position extending substantially outward from the shank for hindering unintentional removal of the distal flange from the lacrimal punctum.
U.S. Pat. No. 6,041,785 discloses a punctal plug that includes a proximal head, a distal body, and a shaft between the head and the body. The shaft of the plug is provided with one or more foldable portions, thereby permitting the length of the shaft to vary depending upon the degree to which the folds are folded or unfolded. In addition, the folds permit the wall of the shaft to easily bend, permitting the head and body of the plug to lie along different axes. As a result, the plug is shaped to accommodate both relatively long and short vertical puncta and the body of the plug may be angled relative to the head to accommodate a variety of anatomical structures.
U.S. Pat. No. 6,016,806 discloses a similar punctal plug that includes accordion-like folds to permit the thin wall of a shaft to easily bend. This permits the head and body of the plug to lie along different axes.
U.S. Pat. No. 6,234,175 discloses a punctal plug design and method for insertion which achieves a one-size-fits-all device for blocking the punctum or canaliculus of a patient. This is accomplished by using specifically defined materials having narrowly-defined glass transition temperature and/or melting temperature properties for fabricating the plug.
PCT Patent Publication No. WO2007/149832 discloses a punctal plug for the delivery of active agent to one or both of the tear fluid of the eye and to the nasolacrimal duct. The plug includes a body, a reservoir contained within the body, and a collarette. The reservoir has at least one opening and contains a polymeric material and at least one active agent.
U.S. Patent Publication No. 2007/0298075 discloses a punctal plug for the delivery of active agent to one or both of the tear fluid of the eye and to the nasolacrimal duct. The plug has a body, a reservoir contained within the body, and optionally a collarette. The reservoir has at least one opening and contains a polymeric material and at least one active agent.
U.S. Patent Publication No. 2007/0299516 discloses a punctal plug for the delivery of active agent to one or both of the tear fluid of the eye and to the nasolacrimal duct that comprise a body, at least one cap, and a collarette.
U.S. Patent Publication No. 2008/0045911 discloses punctal plugs for the delivery of active agents. The plugs have a body throughout which at least one active agent is dispersed or that is coated with a polymeric material containing at least one active agent.
U.S. Pat. No. 6,527,780 discloses a method for inserting punctal plugs into the lacrimal outflow system.
Another type of plug is disclosed in U.S. Patent Publication No. 2007/0021762. The ocular plug is formed from a biodegradable material. The plug includes a shaft and a cap. The ocular plugs are intended to occlude and repair discontinuities in the sclera, whether formed deliberately during injection or surgical foray into the eye or accidentally.
Many plugs are made from silicone and are placed painlessly into the puncta at the slit lamp. They act similar to placing a barrier over the drain of a sink that allows the sink to fill with water. The silicone plugs are popular and reimbursed by insurance for DES treatment.
A major problem with silicone plugs is that such plugs utilize a cap to hold the plug in place. The cap latches onto the eyelid surface, so that it does not slip into the deeper tear duct. The cap may rub on the surface of the eye and irritate it.
The plug must be fitted for size due to the typical differences in tear duct dimension from patient to patient. As a result, obtaining the correct size plug can present a problem.
Another problem with silicone capped plugs is that they can become dislodged or lost. As a result, the benefits of such plugs are negated. The placement of such tiny plugs also presents a challenge.
U.S. Patent Publication No. 2006/0074370 discloses this type of “deeper” punctal plug. The punctal plug is made from an acrylate polymer or copolymer in the form of a solid rod that changes shape with the temperature change that occurs upon insertion into a canaliculus within the lacrimal outflow system. Once inside the canaliculus, the rod absorbs liquid to swell to its original cross section. These types of plugs are commonly referred to as intracanalicular plugs.
Intracanalicular plugs have several disadvantages. The hardened intracanalicular plug can erode in the soft inner wall of the canallculus, which causes granulation tissue and infection. This requires surgical removal.
Similar plugs have been disclosed by Oasis Medical of Glendora, Calif. and Medennium, Inc. of Irvine, Calif. The Oasis Medical plug is sold under the trademark Form Fit®. The Medennium plug is sold under the trademark Smart Plug®.
Other approaches involve different materials or surgical procedures. Temporary collagen plugs that sit below the puncta are also available. However, such plugs only last for about one week.
The principal theory of blocking the outflow of tears is fundamentally sound, as it involves using the patients own tears to lubricate the eyes. The current types of tear plugs all have their unique set of problems as listed above. Therefore, there is need for a plug that is easy to place, effectively blocks the outflow of tears, comfortable, long lasting, easily reversible, and has a low potential for infection.